Table 3 Construction parameters of large diameter drilling of coal seam in 21,201 working face.

From: Investigation of the mechanism and application of pressure relief roadway in preventing rock burst

Pre-pressure relief area

Spacing, m

Depth, m

Angle ,°

Aperture, mm

Distance from base plate, m

Lead relief area

1,2,3

15

Down seam

150

0.5–1.5

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